In general, a fly reel, which is a fishing tool allowing a fishing line to be wound around and unwound from a spool, includes the spool around which the fishing line is wound and a housing on which the spool is rotatably supported.
The fly reel is configured such that the spool is detachably mounted on the housing for easy replacement of the fishing line, that a control force of restricting rotation of the spool is applied to prevent the fishing line from being unwound from the spool, and that the fishing line is wound around the spool without resistance.
A conventional dragging device for generating a control force of restricting the one-way rotation of a spool of a fly reel has been described in Laid-Open Patent Publication No. 1999-0007561 (filed by the present applicant and published on Jan. 25, 1999). Referring to FIG. 1, the dragging device is configured such that a plunger 134 which moves forward due to the rotation of a drag-adjusting knob 140 pushes a second washer 125 toward a flange surface 122 which extends in the radial direction from the rear end of a cylindrical sleeve 120 rotatably mounted onto a main shaft 110, as a result of which the second washer 125 pushes a disk plate 124 to cause a friction contact between the disk plate and the flange 122 of the sleeve 120, which generates a control force of restricting the rotation of the sleeve 120.
A pushing force, which is exerted on the disk plate 124, is transferred to the sleeve 120 via the flange 122, but the sleeve 120 is not pushed due to a shoulder portion 113 disposed on the main shaft 110, so a control force of restricting the rotation of the spool is generated due to the friction between the disk plate 124 and the shoulder portion 113.
A one-way bearing 220 is mounted on the outer circumference of the sleeve 120 to restrict the one-way rotation. When the fishing line is unwound from the spool, the spool and the sleeve 120 are rotated together by the one-way bearing 220, while a control force is generated by the disk plate 124. Meanwhile, when the fishing line is wound around the spool, the linkage operation of the one-way bearing 220 and the sleeve 120 is interrupted, so the spool is freely rotated relative to the sleeve 120, allowing the fishing line to be wound around it.
However, the above configuration has the following problems because the control force of restricting the rotation of the spool is generated by the sleeve placed between the shoulder portion of the shaft and the disk plate. That is, there is a small friction contact area between the shoulder portion of the shaft and the disk plate, so the drag-adjusting knob should be rotated by a strong force to raise pressure in order to increase the control force of restricting the rotation of the spool. In addition, when the spool is detached, the friction surface which makes contact with the sleeve is exposed to the outside, and thus may be contaminated with foreign substances. Moreover, sliding takes place due to water infiltrated into the friction surface, which leads to the reduced control force. Furthermore, the shaft has a complicated section, which leads to a high processing cost.